2nd amp or one bigger amp?

What is your budget?

Typically you'll get more for your budget if you invest in one better amp.

With a tight budget in mine, if you should go with monoblocks, keep in mind that you'll eventually need two aftermarket power cords and/or power conditioners and to get the most from any amplifier, they need to be on a dedicated 20amp circuit and audio grade outlet. With monoblocks, you would need two dedicated circuits.

-IME

look into 2 odyssey stratos monoblocks with the upgrades. or if you have the funds, get 2 classe cam amps. The odyssey is very similiar in sound for 1/3rd the price. As for electrical, 1 single 20 amp circuit would be plenty with 1 good line conditioner. You will not need 2 dedicated lines and 2 line conditioners. I have been at audio shows where they plugged all of there equipment into a 4 port richard gray device or a multiple port ps audio device. If you get a cheaper line conditioner, then you might need more than 1. As for current draw from a 20amp circuit, call an electrician when you get everything setup and he will put a device on the line that will indicate how many amps you are drawing at the panel. I think you will be surprised at how little amps you are drawing. I have 2 monoblocks plugged into a ps audio line conditioner on a dedicated 20 amp circuit. At my maximum listening level, I'm pulling a little over 5 amps at the panel. I could 3 more amps on the circuit and not have any problems.

Have you looked at the Innersound amps? The good thing about the Innersound, besides the good performance from what I have heard, is the trial period and warranty. I'm partial to the McCormack DNA-2 in any configuration and they can be upgraded by SMc Audio. You do get a warranty if you get a McCormack upgrade at SMc, but I don't know if it's transferable.
There is the DNA-500 you can purchase new.
http://www.iar-80.com/

Sounds like you are hooked on tubes and I can understand why you would be. However, if you are not then you might want to consider one of Conrad Johnson's solid state amps like the MF2500 (used) or MF2250.

Or another option; I believe Martin Logans have the capability to run in a bi-amp fashion. If so you may want to purchase a CJ MF2250 ss amp and run it in combination with your MV55 tube amp. The MF2250 would handle the bass section and the MV55 would handle the mids and highs. A friend of mine runs this combo with a Premiere 11a / MF2250 into a pair of KEF's and it sounds great.

I am currently driving a pair of Thiel 3.6's with a CJ 16lsII tubed pre/ MF2500 ss amp. I am extremely pleased with the results.

Chuck

Keep in mind that if you biamp, you will have to match the impedance and output levels of the amps if they are of different types/models. In your instance with a tight budget, I would go for one larger amp. The 11 is a fair choice.